battery question

[tomsic]

so i am buliding an electric gokart and i have a motor with continuous power 4kw. is it okay if i buy battery thats rated for 3000-3500w? probablly i will get lesser power or not?

 

[Functional Artist]

Howdy &

If you're talking about a Lithium battery pack
...& "if" it has a built in BMS rated for use with 3kW - 3.5kW
...then, your 4kW motor may try draw too much current & overheat &/or damage the BMS

 

[tomsic]

Howdy &

If you're talking about a Lithium battery pack
...& "if" it has a built in BMS rated for use with 3kW - 3.5kW
...then, your 4kW motor may try draw too much current & overheat &/or damage the BMS

okey i thought something like this would happen yes, also a question if peak/pulse power of the motor is 15kw that shouldnt damage the battery thats rated 3-3,5kw power motor? i mean its just al pulse for like few seconds or a bit more but only counts the continuous power right?

 

[Functional Artist]

Well, if the battery pack is 48V & rated for use with a 3,000W motor, the draw would be ~62A (3,000W/48V=~62.5A)
...so, the const draw would probably ~40A
...& peak draw would probably be ~80A

For comparison a 14kW (peak) motor could easily draw anywhere from ~100A - 300A (14,000W/48V=~291A)
...which is WAY over the capabilities of a battery pack designed for use with a ~3kW motor

 

[nobled2]

Well, if the battery pack is 48V & rated for use with a 3,000W motor, the draw would be ~62A (3,000W/48V=~62.5A)
...so, the const draw would probably ~40A
...& peak draw would probably be ~80A

For comparison a 14kW (peak) motor could easily draw anywhere from ~100A - 300A (14,000W/48V=~291A)
...which is WAY over the capabilities of a battery pack designed for use with a ~3kW motor

OP would be able to limit the draw from battery with the speed controller wouldn't he??

I guess it depends on which speed controller is used??

 

[Functional Artist]

OP would be able to limit the draw from battery with the speed controller wouldn't he??

I guess it depends on which speed controller is used??

Yup, a user can set the current limits on the higher end speed controllers
...but, with most of the simple/el-cheap-o controllers the only way to limit the current would be to "go easy" on the throttle
...&/or maybe incorporate some kind of a "throttle limiter" (AKA a block(er) under the throttle pedal)